1. Field of the Invention
This invention relates to a system for bioremediation of contaminated media. More specifically, the invention relates to a method and apparatus for removing contaminants from soil and sludge using a hydraulic system to stimulate the effectiveness of microbial action.
2. Related Art
Numerous problems are encountered when attempting to remove hydrocarbon based contaminants from natural soils or man-made media utilizing microbes. It is accepted that a water phase treatment system is required to utilize microbes. It is well known throughout many industries that the introduction of hydrocarbon digesting microbes into a water/solids mixture can result in the complete degradation of the hydrocarbon by the microbes. However, the following problems occur in establishing the water/solids or slurry phase mixture:
A. The ratio of solids to water cannot exceed the system's ability to maintain all solids in a smooth homogeneous slurry. It is recognized in the bioremediation industry this ratio is typically about 10% solids, 90% water, and seldom exceeds 30% solids, 70% water. PA1 B. A "slurry-phase mixture" requires continual mixing of the slurry in order to maintain all solids in uniform suspension. PA1 C. A slurry-phase mixture must consist of very small and uniformly sized solid particles. Without this small and uniform size, a homogeneous slurry cannot be maintained. Particles too large will not remain in suspension (they are too heavy). Particles of different size will require different rates of mixing in order to remain in suspension. Hence a slurry-phase mixture requires that all solids be of uniform size and weight. PA1 D. A slurry-phase mixture must not contain debris (concrete, asphalt, wood products, steel, gloves, clothes, plastic, etc.). PA1 E. Not all soils and man-made media can be placed in slurry-phase, e.g., natural and crushed rock, gravel, stone products, oyster shell (whole or crushed), etc. This material is disposed of in a permitted landfill. PA1 F. A slurry-phase mixture is difficult to attain with heavy clay soils. Generally, clay soils are first dried and then ground in order to break the clay bond.
A general method of the prior art that would attempt to address these problems is as follows. In order to treat a contaminated media in a slurry-phase, the media must be cleaned of all debris. Then all particles that cannot be reduced to a uniform size must be removed. After the soil is "cleaned", it must then be crushed or ground to a uniform size. The processed media is then mixed with water. The solid/water mixture is agitated until all solids are in uniform suspension. Agitation is maintained and the microbial treatment process begins.
These methods are very labor and machinery intensive. The costs are quite high. This method also results in the creation of additional contaminated material (all that was removed from the original media) which must be disposed of in a permitted landfill.
There is an additional method sometimes used to break down clay soils and other media. This method can be broadly classified as soil washing. In order to "wash" soil, a high pressure stream of water is directed at the media to be broken down into smaller sizes. If enough high pressure water is used in this process, one can be assured the shearing action of the water will break down the media. Of course, the problem then becomes the same volume of contaminated media (i.e. a cubic yard of clay is still by volume a cubic yard of clay, but in very small particles) plus, a large amount of contaminated water. The water can be decontaminated using several different methods but at high cost factor. Simply stated, such washing creates a problem greater than the original.